Graveling of wells



April l, 1947. J. E. GAROL.

GRAVELING OF WELLS Filed July 50, 1945 CARR-:ER FLUID 4 7'/ f FIG.

' FIG."

FIG.

ATTORNEY 1 This invention relates Patented pr. 1, 1947 l x :UNITED STATE S vPATENT OFFICE; l

GRAVELING OF WELLS John ElmenGarol, Los Angeles,Calif., assigner-to The Texas Company, New `York, N. Y., a cori poration of` Delaware u Application July so, 1943, serialNo. 496,714

t packing of bore holes'or wells and particularly to gravel packing? in which the lsti-called reverse circulation method of placing the gravel is used.

The principal object of the invention is to pror lplaced in the well cavity by lowering it while atthe graveling orgravel tached to the lower end of a string of tubing. The

granular material is `circulated downwardly by lmeans of a carrier fluid such as drilling mud or` oil,` through the annular u spacejbetween the tubing' string and the casing'of Vthe well, `andthe granular materialis depositedin the well cavity whileY theV carrier jfluid passes into the screen through theYperforations therein and then upwardly to thesuriace. u f p In the `process cgi-introducing gravel in this manner it `isdesirlable. to keep the carrier fluid from bypassing the gravel in the space in which the pack is to be deposited. When `using an ordinary perforated liner or screen the carrier uid may byflass by entering the screen through the upp-er perforations and then `flowing downwardly inside of the screen and back into the cavity through lower perforations. .When this occurs the gravel may bridge in the upper portion or the spacetobe. packed and thus there will be gaps or openings in the resulting deposit. IfV these gaps occur,` the oil to be'` produced will take the path of least resistance through these gaps and,

carrying. :itrsand 'from` the formation, enter the liner or screen Due to the abrasive action of the sand, the screen may be cut away and u damaged to such an `extent that it will have to screen so that there will be no transmission of after. passing downwardly .through the gravelfbeing deposited, then entering the screen atits-lower end and passing upwardly to the surface through the tubing string. In accordance with the invention, the slots or perforatio-ns in the screenwhich are usually cut through the walls of the screenvpipe bymeans of a milling machine are cut almost, but-not quite, all the way through the wall, thus leaving; a thin shell of metal at the inner end of eachslot or perforation. The screen in this condition is' placed in the hole and the gravel depositedaround it by reverse circulation, the carrier liquid being forced to pass through the gravel `being deposited and to enter the screen at its lower end. 'Afterwthe graveling operation hasbeen completed, a sudden high pressure is produced within the screen'as by the explosion of anexplosive cordor fusegthis high pressure serving to break and blow outward- Vly the thin shell metal portions at the end'ofeach slot thusopeningthe slots to permitthepassage of the uid to be produced into the screen.

For a better understanding ofthe invention, reference may be had to the accompanying drawing in which:

Figure l is a vertical elevation through a well showinggravel being deposited around ascreen having perforations which are slightly undercut; Figure 2 is a vertical elevation of a portion of the screen Vshowing an explosive cord in place l preparatoryto being fired, and

fluid through the slots during the graveling operation. This provides for the confining of the `carrier fluid together with the gravel in the an- Figure 3 is an enlarged view of a section of the screen as shown inFigure 2. p

Referring to the drawing; a bore hole `I0 is shown as having been drilled into a producing vmechanical, or hydraulic underreaming to form a cavity I3 within the producing formation. A -4 liner vor a screen member 20 is attached either at its upper or lower end to the lower end of a tubing string 22 extending downwardly from the surface, the lower end of the screen preferably resting on the bottom wall of the cavity i8. A bull plug 24 is shown as attached to the bottom end all the way through the wall of the bull plug.

The screen pipe 20 is provided with. slots or recesses 28 which, as is shown in Figure 2,4 are milled or otherwise cut substantially, but not` quite, all the way through the wall ofV the pipe.

be, forinstance, drilling mud or oil, is pumped into the well casing through a conduit 32. The particlesof gravel 34 pass downwardly with the Obviously many modifications and variations of the invention, as hereinbefore set forth, may

be made without departing from the spirit and Y scope thereof, but only such limitations should be imposed as are indicated in the appended claims.

I claim:

1'. A well screen for use* in a well being gravel packed comprising a pipe member provided with recesses extending radially into the pipe wall from the outer surface and terminating just short of carrier liquid and, since these particles are larger I in diameter than the width of the slots 26, these particles are deposited in the cavity l81`to"form a y Y gravel or lter pack around the screen 2U. The carrier liquid passes inwardly through the slots 26 of the bull plug 24 and then returns to the surface through the tubing string 22. During the y graveling operation, the carrier fluid cannot enter through the side walls of the screen 26 since the recesses 28 do not extend all the way through the walls. Consequently the carrier fluid cannot by-pass the gravel by passing inwardly and downwardly throughthe screen, and as a result cavities or gaps in the resulting gravel pack are avoided. When enough gravel has been deposited to'fill the cavity I8 up to the casing I4 or at least above the uppermost slots 28, the circulation of the gravel and carrier liquid is discontinued and the space between the upper end of ,intoy the screen Zllby means of a wire cable 38. YThe wires 38 of the cable are connected tothe cord 36 and :in seriesv with a source oftelectrcity 40 and a suitable switch 42 atl the surface. By closing the switch 42 electric current will kpass to the cord 36 causing this to explode substantially instantly throughout the length of the screen pipe and the sudden high pressure thus exerted willrupture the thin metal shell 30 at the inner end of each slot 28, the particles of metal being blown outwardly thusopening the slots 28 to permit passage ofthe formation fluid into the screen and then upwardly to the surface through the tubing string 22.

Although it is preferred to use the explosion of a cord 36 for rupturing the thin wall portions 30 to open up the perforations, it is also contemplated that the high pressure can be generated by other means such as by the explosion of one or more compact charges or the explosion of a gas or aliquid or a gaseous mixture which may be placed in the liner after the graveling operation.

vInstead Aof utilizing an explosion,'a,sudden high v` tubing 24.

i4 is preferably sealed by means of a the inner surface of the wall so as to leave a vthil'l Shell Of the metal 0f the Wall at the inner end of eachrecess. 2. Ay well screen for use in a Well being gravel packed -comprising a pipe member provided with screenslots extending radially into the pipe wall from the outer surface andterminating just short ofv the inner surfaceof the wall so as to leave a thin shell of the metal of the wall at the inner end of each slotfsadmetal shell being suiil.

ciently weak as compared with the adjacent wall portions as to allow it to 'be'disrupted by an abnormal increase in fluid pressure within the pipe member. y

3. A wellscreen for use in a well being gravel packed comprising a metal pipe member provided with closely spaced screen slots extending par.'- tially through the pipe wall from the outside thereof, the depth ofeach slot being slightly less than the thickness of the pipe wall whereby a thin layer of the pipe wall metal remains at the inner end of each slot, said thin metal layer being adapted to be disrupted by a sudden abnormal increase in fluid pressure within the pipe but sufficiently strong to withstand the fluid pressure normally occurring on the exterior-of the screen pipe `during the placing of gravel by' reversecirculation. .p

4,. A well screen yfor use in a well to bey gravel packedcomprising a metal pipe member vhaving an imperforate interior Wall surface, Ythe exterior Ywall surface of said member being provided with a plurality of slot-like recesses extending inward- 1y toward said interior surface, the depth of each of said recesses being slightly' less than the thick- `ness of thewall of the pipe member so as'toprovide a thin, frangible shell of. the metal of the pipe member at the inner end of 'each recess.

' JOHN ELMER GAROL.

REFERENCES CITED The following references are of file of this patent:

record in the t AUNITED STATES P A Ts 

